1. The Field of the Invention
The present invention relates to a structure of button for an electronic product, and more particularly to a structure of button comprising a parallel bar set positioned between an upper lid and a chassis such that the length of a positioning bar of the parallel bar set limits the moving distance between the lid and the chassis.
2. Description of Related Art
Presently, the well-developed electronic technology produced advanced electronic products that provide convenience in our daily activities. Most electronic products require an input device for enabling the user to input letters, numbers or commands enjoy the functions provided by the electronic products. Examples of such input devices include mouse, keyboard or joystick and light beam gun for games. The development of these products later led to development, for instance, from buttons on the keyboard for the conventional desktop computer to the buttons for the notebook computer. The notebook computer being lighter, thinner, shorter and smaller than a desktop computer, the structure of the buttons of the notebook computer cannot be same as the ones applied in the keyboard of the desktop computer. Extensive research and development resulted into invention of a new scissor structure and new method of installing the buttons on the scissor structure that can be applied to a notebook computer. Referring to FIGS. 7 and 8, an exploded view and a side view of a conventional scissors structure of a button for an electronic product are respectively shown. As shown, the button comprises a first supporting rack A and a second supporting rack B. The second supporting rack B has an axle B1, which is axially fitted into the groove A1 of the first supporting rack A. The sliding element A2 of the first supporting rack A and the sliding element B2 of the second supporting rack B are fitted into the sliding groove C1 of the base C and the sliding groove D1 of the cap D respectively to position the securing element A3 of the first supporting rack A into the axial hole C2 of the base 3 and the securing element B3 of the second supporting rack B into the axial hole D2 of the cap D axially. When the user press the cap D, the cap D will come down with the force of the first and second supporting racks A and B.
However, there are several defects with the conventional scissors structure, the buttons for the scissors structure and the installation method described as follows.                1. The first and second supporting racks A and B of the conventional buttons have a fixed the moving distance between the base C and cap D, thus it is difficult make any modification for fitting various specification of a variety of electronic products. Accordingly, a specific structure is designed for each product, and therefore the manufacturing cost is substantially increased.        2. The scissor structure of the conventional button is consisted of the first and second supporting racks A and B, the axle B1 and the groove A1 will be dislodged due the friction after repeated pressing operation causing dislocation and may jam up the first and second supporting racks A and B.        3. The cap D of the conventional button requires a sliding groove D2 for allowing the first supporting rack A to move when the cap D comes down, thus the size of the cap D is limited and cannot be smaller and therefore cannot fit the specification of the electronic products of the present trend of being lighter, thinner, shorter and smaller.        
Therefore, how to solve the above defects of the conventional design has become an important issue for the manufacturer in the field.